Induction heating device

ABSTRACT

The invention is a heating device having a primary winding connected to an A.C. generator and a secondary winding to which an inductor is connected. It is characterized in that the secondary winding is made in a single arcuate sheet metal plate housed within the primary winding, in that there is provided a pair of appending members extending the ends of the secondary winding and forming a sandwich enclosing a thin layer of insulating material. The appending members are first directed inwardly of the secondary winding. The heating inductor is connected to these two appending members.

United States Patent [191 Trine Nov. 19, 1974 [21] Appl. No.: 373,484

[30] Foreign Application Priority Data June 26, 1972 Belgium 4145 [52] US. Cl. 2l9/10.79, 219/1075, 336/79, 336/82 [51] Int. Cl. H0511 5/06 [58] Field of Search 219/1075, 10.77, 10.79; 336/90, 82, 84, 79, 123

[56] References Cited UNITED STATES PATENTS 2,151,035 3/1939 Kennedy 219/1075 2,181,899 12/1939 Kennedy 2l9/10.75 2,314,865 3/1943 Bierwirth .Q 219/1075 2,484,650 10/1949 Ross 219/1075 X 2,662,162 12/1953 Blok 219/1075 X 3,300,614 1/1967 Sorensen 219/10.75 X

3,720,803 3/1973 Lewis 219/10 .79

FOREIGN PATENTS OR APPLICATIONS 1,025,811 4/1953 France 219/1075 650,184 2/1951 Great Britain 219/1075 Primary Examiner-Bruce A. Reynolds Attorney, Agent, or Firm-Raymond A. Robic; Arthur Schwartz [5 7] ABSTRACT The invention is a heating device having a primary winding connected to an A.C. generator and a secondary winding to which an inductor is connected. It is characterized in that the secondary winding is made in a single arcuate sheet metal plate housed within the primary winding, in that there is provided a pair of appending members extending the ends of the secondary winding and forming a sandwich enclosing a thin layer of insulating material. The appending members are first directed inwardly of the secondary winding. The heating inductor is connected to these two appending members.

9 Claims, 4 Drawing Figures PATENTEL 30V 1 9 I974 3,849,625 sum 10F a INDUCTION HEATING DEVICE The present invention relates to new induction heating device.

It is already known to use devices for heating by induction which comprise a primary winding connected to an alternating current generator and a secondary winding to which a heating inductor is connected. Such a device is disclosed for instance in Swiss Pat. No. 276,212. In this known device, the secondary winding is arranged inside the primary winding. Furthermore, the secondary winding is movable with respect to the primary winding. Arranging a secondary winding inside a primary winding is not a current technique and is, besides, the source of several obvious inconveniences. However, the solution in the above-mentioned patent has been proposed in view of the great difficulty to master the problem of connecting an inductor to the ends of a secondary winding.

An object of the present invention lies in the provision of a device for heating by induction in which the secondary winding is arranged, as is generally the case, inside the primary winding and in which the difficulties of joining an inductor to the ends of the secondary winding are resolved in a satisfactory manner. A subsidiary object is to retain the possibility of making the secondary winding movable with respect to the primary winding.

In order to obtain the above results, the heating device according to the invention is characterized by a secondary winding made of a single curved sheet metal plate housed within the primary winding, by two appending members extending the ends of the secondary winding and forming a sandwich enclosing a thin layer of insulating material, directed inwardly of the secondary winding and by an inductor connected to the said two appending members.

The invention is further explained hereinafter with respect to a few embodiments having reference to the appended drawings wherein:

FIGS. 1, 2 and 4 are perspective views of different embodiments of the invention;

FIG. 3 is a partial perspective view of a particular type of opening inductor. An induction heating device according to FIG. 1 comprises a primary winding wrapped in a hollow cylinder 1 made of insulating material, for instance epoxy resin, connected to an A.C. generator 2 through taps 3 allowing the selection of an appropriate number of turns of this primary winding. A secondary winding is housed within this hollow cylinder 1, being constituted by a single copper sheet 4, curved and open along two generatrices and 6. The sheet metal plate 4 is extended, at the two generatrices 5 and 6, by two appending members 7 and 8 defining a sandwich containing a thin layer of insulating material. The latter may be air, micaceous polytetrafluoroethylene etc. or a combination of several different insulating materials. The appending members 7 and 8 are directed inwardly of the curved sheet metal plate 4. Their width is preferably greater than one quarter of the width of the curved plate 4 and their length, along the generatrices 5 and 6, is appreciably greater than the length of curved plate 4. In the case of FIG. 1, the appending members or appendices 7 and 8 constitute the frames of a window through the opening of which the hollow cylinder 1 passes. To pass this cylinder 1 through the opening, the frames are screwed where flanges 9 and 10 are provided. An inductor II is connected between the appendices 7 and 8 to allow heating of a part 12 to be processed. Cooling of the primary winding in the cylinder 1 may be obtained by means of water circulating through conduits l3. Cooling of the secondary winding may likewise be achieved by means of water, for instance by copper tubes welded on the plate 4, on the appendices 7 and 8 and on the inductor 11 but it is often possible to be content with natural cooling as shown in FIG. 1. The arrangement according to FIG. I has the advantage that the connections at the ends of the secondary winding are perfectly symmetrical. Consequently, their disturbing effect is reduced to a minimum, more especially since because of the substantial width of the appendices 7 and 8, the current concentration is small. Due to the small distance between the appendices 7 and 8, there is a tendency for a closeness effect to produce in the appendices identical current dis tributions.

The curved plate 4 may slide on the inner surface of the hollow cylinder 1 and carry out rotation movements namely of an angle greater than This makes it possible to remove the part 12 to be processed from the inductor 11 so as to allow access to lifting and handling means, not shown. On the other hand, this mobility makes it possible, during the process, to follow with the inductor any unevenness such as 14 in the part to be treated. To achieve this, the inductor 11 may be provided with a pad sliding or rolling on the part to be processed, for example a ball or a corundum tube 45. It is obvious that a certain mobility in the direction of the axis of the windings may also be provided by the selection of the dimensions of the opening of the said window formed by the appending members and used, for instance, to open up the inductors without opening contacts or to follow, by means of an appropriate spring, not shown, deformations of the part under heat.

In FIG. 2, a hollow body 15 made of insulating material and of oblong cross-section, has two housings of circular cross-section containing two primary windings. In the housing of circular cross-section are inserted two secondary windings l6 and 17 each provided with a pair of appending members l8, l9 and 20, 21, respectively. Each pair of appending members feeds a halfconductor 22 and 23 through which a part 24 to be heated may be moved. The inductor may open up, without breaking any contacts, by pivoting the assembly l6, l8, 19, 22 about the axis of the primary winding 16 and by pivoting the assembly 17, 20, 21, and 23 about the axis of the winding 17. It is possible to move only one of such assemblies 16-22 and 17-23. The openable inductor may also be conceived according to the embodiment illustrated in FIG. 3 in which the corresponding parts carry the same reference numerals as those used with respect to FIG. 2.

There is shown in FIG. 4, an embodiment making possible a complete and uninterrupted rotation of an inductor about an axis 24. The inductor itself is not shown. It may, for instance, have the shape of a window 11 as shown in FIG. 1 and is located in the extension of the two appending members 25 and 26 of the secondary winding 27. To facilitate understanding of the drawing, the winding 27 is moved out of its housing inside a primary winding 28 of the bayonet type. The winding 27 may be rotated about its axis 29 by means of a suspension formed of four rollers 30 made of insulating material and secured to lugs 31. To help in understanding the drawing, one of the lugs 31 is not provided with its roller. This missing roller is secured to the lug 31 for free rotation after insertion of the winding 27 in the winding 28. The rollers 30 are provided with a shoulder providing a well-defined spacing between the winding 27 and the winding 28, whereas the end of each roller 30 rolls on an edge of the winding 28. The latter is fed by two appending members 32 and 33 of a rotary secondary winding 34. The latter rotates about the axis 24 inside a hollow cylinder 35 made of insulating material and housing a primary winding. It may be provided with bearings preferably made to insulating material such as glass, epoxy resin etc. A driving pulley 36 actuated by a motor 37 drives the secondary rotary winding 34 by means of a belt 38 housed in a sheave 39 pressed in the sheet metal plate forming the winding 34. If a part such as 40 is to be heated, it is sufficient to palce it even with a wide eccentric tolerance about the axis 24 and to bring it close to the inductor, not shown, at the end of the appending members 25, 26. This inductor is applied either directly against the part to be heated and is then provided with a friction pad, or against an appropriate guide cam or rail, not shown, by means of a resilient return member, for instance a spring 43 extended between a hole or eye 41 in the appending member and a hole or eye 42 in the appending member 32. It is obvious that the suspension of the spring 43 in the eyes 41 and 42 requires the use, for instance of an insulating member 44. When the winding 34 rotates about the axis 24, it drives the winding 28 and consequently the inductor at the end of the appending members 25 and 26 in a continuous rotation. The spring 43, stretched between the eyes 41 and 42, allows the inductor simultaneously to carry out oscillating movements about the axis 29 which itself turns about the axis 24. The inductor may thus follow the contour of a piece as complicated as piece 40 of FIG. 4. It is obvious that the assembly of parts 25 to 39 and 41 to 44 may be mounted on a movable equipment and handled by carriages or cranes to serve for example as apparatus for cutting and/or welding and/or annealing in the construction industry and in the repair of installations or metal buildings of very large dimensions.

In order to take advantage to the maximum of the mobility of the secondary winding within the primary winding, several devices may be considered to ensure permanent or oscillating, continuous or jerky rotary motions. Such devices are, for instance: a friction pad or bearing roller on the inductor which make it possible to follow the unevenness of the piece to be heated due to the weight of the inductor. If the weight of the inductor does not in the desired direction, a counterweight system working through cables and pulleys or a spring may be provided. If the part to be heated reaches the softening point of the heated material, the friction pad or the bearing roller may not be located on the inductor itself but must be displaced to a more appropriate location, for instance, on anarm solid with the inductor and, rather than slide or roll on the part itself, an appropriate guiding rail may be provided.

I claim:

1. An induction heating device comprising:

a. a primary winding and an A.C. generator connected thereto;

b. a hollow body of insulation material in which is embedded said primary winding and which defines at least a housing for a secondary winding;

c. a secondary winding made of single curved sheet metal plate with ends thereof being directed inwardly of said curved plate and spaced from one another, said secondary winding being rotatably glidable over an angle more than relative to and within said housing provided in said hollow body;

d. a pair of spaced appending members each extending from one of said plate spaced ends. a portion of said members being directed inwardly of said curved plate;

e. a layer of insulation between said appending members; and

f. a heating inductor connected to said two appending members.

2. A device as claimed in claim 1, wherein said heating inductor is substantially symmetrical relative to the plane of symmetry perpendicular to the axis of said secondary winding and wherein said appending members have outward directed portions thereof also symmetrical with respect to said plane of symmetry.

3. A device as claimed in claim 1 wherein said hollow body in which is embedded at least one primary winding defines a plurality of housings for a plurality of secondary windings located in rotatably glidable relationship within said housings.

4. A device as claimed in claim 1, wherein said secondary winding is rotatable and means to rotate it about an axis inside said primary winding substantially parallel to the axis of said primary winding.

5. A device as claimed in claim 1, wherein said inductor is an open inductor and at least a portion thereof is connected to the secondary winding rotating inwardly of the hollow body including the primary winding.

6. A device as claimed in claim 1, including means to bring said secondary winding into continuous rotation.

7. A device as claimed in claim 1, including a resilient device to return said inductor into a limit position.

8. An induction heating device comprising:

a. a primary winding and an AC. generator connected thereto;

b. a hollow body of insulation material in which is embedded said primary winding and which defines at least a housing for a secondary winding;

c. a secondary winding made of a single curved sheet metal plate with ends thereof being directed inwardly of said curved plate and spaced from one another, said secondary winding being rotatably glidable relative to and within said housing provided in said hollow body;

d. a pair of spaced appending members each extending from one of said plate spaced ends, a portion of said members being directed inwardly of said curved plate;

e. a layer of insulation between said appending members;

f. heating inductor connected to said two appending members; and

g. means to permit said secondary winding to move relative to said hollow body including the primary winding in the direction of the axis of said secondary winding.

9. An induction heating device comprising:

A. a first primary winding and AC. generator connected thereto;

b. a hollow body of insulating material in which is embedded said first primary winding and which defines a housing for a first secondary winding;

0. a first secondary winding made of a first single d. a first pair of spaced appending members each extending from said first plate spaced ends, a portion of said members being directed inwardly of said first curved plate;

e. a layer of insulation between said appending members;

f. means to rotate said first secondary winding about an axis inside said first primary winding;

g. a second primary winding electrically connected to and mechanically supported by said appending members of said first secondary winding;

h. a second secondary winding rotatably supported by said second primary winding, said second secondary winding being made of a second single curved sheet metal plate with ends thereof being directed inwardly of said second curved plate and spaced from one another;

. a second pair of spaced appending members each extending from said second plate spaced ends, a portion of said second members being directed inwardly of said second curved plate;

. a heating inductor connected to said two second appending members; and

. a resilient device fixed between a point of said second appending members and a point of said first appending members to apply said inductor on a workpiece to be heated. 

1. An induction heating device comprising: a. a primary winding and an A.C. generator connected thereto; b. a hollow body of insulation material in which is embedded said primary winding and which defines at least a housing for a secondary winding; c. a secondary winding made of single curved sheet metal plate with ends thereof being directed inwardly of said curved plate and spaced from one another, said secondary winding being rotatably glidable over an angle more than 90* relative to and within said housing provided In said hollow body; d. a pair of spaced appending members each extending from one of said plate spaced ends, a portion of said members being directed inwardly of said curved plate; e. a layer of insulation between said appending members; and f. a heating inductor connected to said two appending members.
 2. A device as claimed in claim 1, wherein said heating inductor is substantially symmetrical relative to the plane of symmetry perpendicular to the axis of said secondary winding and wherein said appending members have outward directed portions thereof also symmetrical with respect to said plane of symmetry.
 3. A device as claimed in claim 1 wherein said hollow body in which is embedded at least one primary winding defines a plurality of housings for a plurality of secondary windings located in rotatably glidable relationship within said housings.
 4. A device as claimed in claim 1, wherein said secondary winding is rotatable and means to rotate it about an axis inside said primary winding substantially parallel to the axis of said primary winding.
 5. A device as claimed in claim 1, wherein said inductor is an open inductor and at least a portion thereof is connected to the secondary winding rotating inwardly of the hollow body including the primary winding.
 6. A device as claimed in claim 1, including means to bring said secondary winding into continuous rotation.
 7. A device as claimed in claim 1, including a resilient device to return said inductor into a limit position.
 8. An induction heating device comprising: a. a primary winding and an A.C. generator connected thereto; b. a hollow body of insulation material in which is embedded said primary winding and which defines at least a housing for a secondary winding; c. a secondary winding made of a single curved sheet metal plate with ends thereof being directed inwardly of said curved plate and spaced from one another, said secondary winding being rotatably glidable relative to and within said housing provided in said hollow body; d. a pair of spaced appending members each extending from one of said plate spaced ends, a portion of said members being directed inwardly of said curved plate; e. a layer of insulation between said appending members; f. heating inductor connected to said two appending members; and g. means to permit said secondary winding to move relative to said hollow body including the primary winding in the direction of the axis of said secondary winding.
 9. An induction heating device comprising: A. a first primary winding and A.C. generator connected thereto; b. a hollow body of insulating material in which is embedded said first primary winding and which defines a housing for a first secondary winding; c. a first secondary winding made of a first single curved sheel metal plate with ends thereof being directed inwardly of said first curved plate and spaced from one another, said first secondary winding being located in rotatably glidable relationship within said housing provided in said hollow body; d. a first pair of spaced appending members each extending from said first plate spaced ends, a portion of said members being directed inwardly of said first curved plate; e. a layer of insulation between said appending members; f. means to rotate said first secondary winding about an axis inside said first primary winding; g. a second primary winding electrically connected to and mechanically supported by said appending members of said first secondary winding; h. a second secondary winding rotatably supported by said second primary winding, said second secondary winding being made of a second single curved sheet metal plate with ends thereof being directed inwardly of said second curved plate and spaced from one another; i. a second pair of spaced appending members each extending from said second plate spaced ends, a portion of said second members being directed inwArdly of said second curved plate; j. a heating inductor connected to said two second appending members; and k. a resilient device fixed between a point of said second appending members and a point of said first appending members to apply said inductor on a workpiece to be heated. 